This invention relates to vehicle security apparatus. It relates more particularly to an anti-theft locking system for automobiles and the like which can be actuated by the vehicle operator to disable the vehicle's ignition system, secure the automobile hood and activate a passive alarm system when the vehicle is unattended.
Security systems for safeguarding automobiles have been in use for many years. One commonly used anti-theft lock of this type is depicted in FIG. 1 of the drawings herein. It comprises a tubular housing 10 having a pair of intergral ears 10a extending laterally from the housing at the forward end thereof. At the roots of these ears there is an opening 12 into the housing which is normally closed by a strap 14 which is secured to the two ears by a pair of sleeve rivets 16. Slidably positioned in the forward end segment of housing 10 is a cylindrical barrel 18. Attached to the end of that barrel is a stiff, but flexible, wire 22 which extends from the opposite end of housing 10. Wire 22 is one component of flexible hood lock cable 24, the other component of which is a sheath 26, the forward end of which is connected to an annular plug 28 seated at the rear end of housing 10.
The lock barrel 18 incorporates a spring loaded retractable latch 32 which is mounted in the side of the barrel and normally projects upward therefrom into housing opening 12 where it engages detent 34 formed at the underside of strap 14. That detent has two steps 34a and 34b and when the strap is riveted to the housing ears, those forward and rear steps project down greater and lesser distances into the housing opening 12. Barrel 18 is slidable in housing 10 between an extended unlocked position wherein latch 32, partially extended, engages detent step 34a thereby preventing further outward movement of the barrel and a retracted locked position. In the latter position, the barrel latch 32, fully extended, engages behind detent step 34b so that the barrel is retained in that locked position. A coil spring 36 compressed between plug 28 and the inner end of the barrel urges the barrel toward its extended position.
Barrel 18 also includes a lock cylinder 42 which cooperates with latch 32 so that when the vehicle operator inserts a key K into the cylinder and turns the key, the cylinder turns, thereby retracting latch 32 partway into the barrel so that it is retracted from detent step 34b allowing the barrel to spring to its extended unlocked position where the latch engages step 34a.
In use, the lock is attached to the underside of the vehicle dashboard by bolts extending through the sleeve rivets 16 in the ears 10a. The flexible cable 24 extending from the lock is conducted to the forward end of the vehicle where the free end of the cable sheath 26 is anchored to the vehicle frame, while the free end of the wire 22 is connected to a hood lock. When the barrel 18 is moved to its extended position, the motion of the wire 22 unlocks the hood lock so that the operator can gain access to the engine compartment. On the other hand, when the barrel is pushed to its locked position, the accompanying motion of the wire 22 locks the hood lock thereby securing the engine compartment.
A locking system such as this also invariably incorporates an electrical hood lock switch which is closed when the barrel 18 is in its locked position in order to disable the vehicle's ignition system and/or to activate a passive alarm system installed in the vehicle. In the conventional anti-theft apparatus depicted in FIG. 1, that electrical switch comprises an annular metal contact 46, similar to a washer, mounted to the forward end of plug 28 inside housing 10. An electrical lead 48 connected to that washer extends out of the housing and is led into the engine compartment of the vehicle. The other switch contact is a brass collet contact 52 which encircles the cable wire 22 adjacent to the inner end of barrel 18. A spring 51 compressed between the contact 52 and the barrel urges the contact toward a stop 53 on wire 22. Contact 52 is grounded by way of cable 24 to the vehicle frame so that when barrel 18 is moved to its retracted locked position, contact 52 engages contact 46 thereby connecting lead 48 to electrical ground.
Although the lock depicted in FIG. 1 has been installed on numerous vehicles, it has several disadvantages which make it somewhat vulnerable and limit its ability to adequately protect the vehicle in which it is installed. More particularly, the lock housing 10 and strap 14 are made of so-called white metal which is not a very strong material and may be cracked by a sharp blow from a hammer. Also, as described above, the housing with its strap 14 is a two piece structure. Therefore, it can be penetrated relatively easily by removing or cutting the bolts connecting the housing ears 10a to the vehicle dashboard and inserting a pry bar under one end of the strap 14 and prying it away from its housing ear sufficiently to break rivet 16 and then bending back the strap as shown in FIG. 1. Since the detent 34 is integral to the strap, it is pulled away from barrel latch 32 so that the barrel 18 is free to be sprung to its extended position even though its cylinder is still in the locked position. This barrel extension disables any alarm system controlled by the lock and releases the hood lock giving the thief access to and control over the vehicle as though the anti-theft apparatus was not present at all.
Another weakness in prior locks of this type stems from the fact that the switch contacts 46 and 52 do not always effect a good electrical connection when the barrel 18 is pushed to its locked position. This seems to be due to dirt and oxide build-up on the relatively large-area engaging surfaces of the switch contacts and the problem usually becomes progressively worse with the passage of time. The upshot is that when the barrel is pushed to its locked position, the switch does not always close to deactivate the car's ignition system.
The most important disadvantage of prior locks of this general type is the inability to repair them. In other words, once the lock is assembled and installed, there is no possibility of gaining access to the interior components of the lock without destroying the lock. This is because, as seen in FIG. 1, once the strap 14 is riveted to housing 10, there is no way to retract latch 32 from detent step 34a to permit barrel 18 to be removed from the housing without either breaking the lock housing or the rivets 16. Therefore, if spring 36 should break, or if the switch contacts should become dirty so that the switch no longer functions properly, there is no possibility of making repairs to the lock. As a result, the entire lock becomes useless and must be replaced. Thus, the malfunction of a relatively inexpensive internal component of the lock can result in a high cost outlay.